[Buildroot] nios2 : gcc 4.9.x buildroot toolchain broken

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Brendan Heading,

On Mon, 27 Jul 2015 21:28:21 +0100, Brendan Heading wrote:

> While looking at the dmraid build bug on nios2 I noted that it is not
> possible to build a buildroot toolchain based on GCC 4.9.x for that
> platform.
> 
> You can reproduce the problem using the following (one-line) defconfig :
> 
> BR2_nios2=y
> 
> I tested it against the commit : 5ccde01652bc41da325bf4c9a5abbf0031080784
> 
> The error is as follows :
> 
> =============
> ../../../libgcc/config/nios2/linux-atomic.c:23:24: fatal error:
> asm/unistd.h: No such file or directory
>  #include <asm/unistd.h>
>                         ^
> compilation terminated.
> =============
> 
> The problem only occurs on GCC 4.9.x. GCC 5.x builds fine.
> 
> Someone already submitted a patch to fix this :
> 
> http://lists.busybox.net/pipermail/buildroot/2015-February/119084.html
> 
> The submitter promised to do some more work but it seems to have been left
> that way since last February.
> 
> We can either :
> - disable GCC 4.9.x for nios2 (leaving 5.x as the only supported buildroot
> toolchain)
> - integrate & test the above patch
> 
> What does everyone think ? Given that the above patch seems to be
> considered incomplete maybe we should disable nios2 4.9.x for now until the
> required additions have been submitted.

Hum, that's interesting. I indeed saw that gcc 4.9.3 was not building
properly for NIOS II. However, gcc 4.9.2 built fine for me. Look at
http://autobuild.buildroot.org/toolchains/tarballs/br-nios2-full-2015.05.tar.bz2:
it is a NIOS II gcc 4.9.2 toolchain generated by Buildroot.

So I don't really understand how Ezequiel fall into the problem of
<asm/unistd.h> with gcc 4.9.2. But I did indeed fall into this problem
with gcc 4.9.3.

Or maybe the problem is *not* gcc version related only, but also
related to the kernel headers version?

But in any case, Ezequiel's patch seems fine to me, I'll try to apply
something similar.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com